1. Field of the Invention
The present invention relates to a method of creating a multiple of virtual Serial Advance Technology Attachment (SATA) ports in a disk array controller, and more particularly to a software method used for supporting a SATA disk array system, so that the SATA disk array can support virtual drives and several corresponding storage units similar to a single channel of a SCSI disk array and also can achieve a low pin count and a high-frequency transmission by a serial bus.
2. Description of the Related Art
Hard disk is one of the popular data storage devices having the feature of a high capacity, and thus becomes an indispensable storage device. In recent years, the transmission interface between hard disk and computer is developed from small computer system interface (SCSI) introduced at early 1980 to the integrated drive electronics (IDE) introduced at late 1980. Regardless of IDE disk interface or SCSI disk interface, a bus interface is adopted and each device of the bus topology requires a unique ID code, such as each IDE bus supports two sets of devices, and each set has a code. For instance, the SCSI disk interface can support eight sets of devices, and the wide SCSI can support 16 sets of devices, and a high-end SCSI interface can support up to 127 devices. Although a SCSI disk comes with good expandability and reliability, it is a high-priced product, and thus the IDE interface is still the mainstream for the interface of personal computers. In the IDE interfaces from Ultra ATA to Ultra ATA/66, and then to the current Ultra ATA/100 or Ultra ATA/133, the Ultra ATA/133 has encountered a bottleneck on the transmission speed, and the transmission speed no longer can meet the requirements of data transmission of a hard disk anymore. Therefore, a new specification is established, and the Serial ATA Organization establishes a SATA specification with the features of a low pin count and a high-frequency transmission (from 150 MB/s of Version 1.0 to 300 MB/s and 600 MB/s of versions 2.0 and 3.0). Therefore, the Serial ATA is expected to take over the Ultra ATA/133 and become an industrial standard of the storage interface for of the next generation of personal computer, and the Serial ATA inherits the advantages of the traditional ATA software compatibility and low price, and it also overcomes the limitation of the ATA that can be applied to the Direct Attached Storage (DAS) only, and the SATA extends its applications to Storage Area Network (SAN) and Network Attached Storage (NAS), and thus manufacturers and users have high expectations on the development of SATA. In addition to the high transmission speed, the improved Serial ATA cable and connector specifications allow users to integrate a hard disk with a flat cable easily. Since the contact point of the flat cable is designed as a goldfinger, therefore users do not have to worry about bending the pins while installing or removing the flat cable. With a good foolproof design, users can install a connector easily without the need of visual adjustment and inspection. The Serial ATA cable is slender and does not occupy much space of the computer housing that helps improving the air flow and heat dissipation of a computer system.
The Redundant Array of Inexpensive Disks (RAID) technology was first developed by a group of researchers at the University of California, Berkeley in 1987. After going through several generations of development, users have different requirements on data backup and generally adopt the high-priced SCSI interface or a low-priced IDE interface. Since the SATA disk has a high transmission rate and an affordable price, therefore SATA disks are recommended to be used as a storage device for data storage and backup. Referring to FIG. 1, the structure includes a computer host system 10 connected to a SATA disk array system 20 through an electric port 11, and the disk array system 20 has a disk array controller 30 connected to a disk set 40, and the disk set 40 includes a plurality of SATA disks 41, and the disk array system 20 can be set to different levels including RAID 0, RAID 1, RAID 2, RAID 3, RAID 4 and RAID 5 for the data storage and backup. If the computer host system 10 issues an instruction for reading or storing data, the disks 41 in the disk array system 20 will update and backup the data synchronously. Since the SATA interface is restricted by its point-to-point connection and transmission, therefore a single SATA electric port 11 can correspond to a logical disk set only. Although the SATA interface comes with a high-speed I/O transmission architecture, it cannot achieve the multi-driving access effect, and thus the SATA interface cannot meet user requirements when a large quantity of data is accessed.